Conventional wisdom says incumbents below 50 are vulnerable. Well, two of the three Republicans running to replace him are now above 50, and the third is at 49.

Except for the extraordinary circumstances of President Bill Clinton’s second midterm after impeachment and President George W. Bush’s first midterm after the 9/11 attacks, the historical record shows midterm elections are always bad for the party of the President. Clinton and Bush themselves found that out in 1994 and 2006 respectively. 2010 appears to be a continuation of the normal trend, and Democrats all over the country are unusually weak.

Reid is no stranger to close elections, having beat out now-Senator John Ensign by 401 votes in 1998, but he had an easy time in 2004, outperforming John Kerry by 96,000 votes to win 61-35 while Kerry lost 48-51. This year though, the polls suggest he won’t beat out a national Republican trend.